Tripoli, Libya (CNN) -- NATO has agreed in principle to take the lead in protecting Libyan civilians, said the top commander of a U.S. mission that also is handing over control of a no-fly zone in the war-torn country.

Gen. Carter Ham, commander of U.S. Africa Command, also said on CNN's "The Situation Room" Friday that removing leader Moammar Gadhafi by military means is not the aim of the mission and that the coalition is not arming rebel forces.

And the general claimed "we have achieved already a large degree of success" -- including an arms embargo, the no-fly zone and the halting of loyalist troops near the rebel-held city of Benghazi.

President Barack Obama will update the nation at 7:30 p.m. ET Monday from the National Defense University at Fort McNair in Washington, D.C., the White House announced.

NATO this weekend is expected to take over control of the no-fly zone from the United States and finalize procedures on protecting civilians.

But Ham acknowledged that challenges remain.

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"We find these regime forces taking cover inside built-up areas where they know -- because of our concern for civilian casualties -- that we won't strike in there," he told CNN'S Wolf Blitzer.

Loyalist snipers, along with armored units, continue to be a threat.

"It is a tough, tough challenge for us," said Ham, speaking from Stuttgart, Germany. "When we see regime forces attacking civilians, we will do everything we can to stop those attacks."

Not long after allies unleashed cruise missiles against Gadhafi air defenses last Saturday, Obama told Americans he wanted the United States, which has headed the military campaign, to hand over control of the enforcement of a U.N. Security Council resolution.

The resolution called for the protection of Libyan civilians and the enforcement of the no-fly zone.

NATO, which includes the United States, will lead both efforts.

The United States has been treating the protection of civilians as part of the mission, and that activity will continue regardless of the command structure, Navy Vice Adm. Bill Gortney said.

"Job one is to protect the Libyan people and the job doesn't change because we have a new boss," he said, briefing reporters at the Pentagon.

Obama on Friday conducted a conference call and meeting with congressional leaders to provide an update on the conflict and attempt to address their concerns about the mission's organization, cost and consequences. Democrats appeared more satisfied than Republicans.

Meanwhile, coalition fighter planes in a 24-hour period took out seven Libyan tanks it claims were threatening civilian populations, including in the city of Ajdabiya, authorities said Friday.

Although Gadhafi is feeling the pinch of more than 850 air sorties, the "regime is still able and still determined to reinforce their positions," Gortney said.

British Tornado fighter jets identified Libyan tanks with their weapons pointed north toward Ajdabiya and destroyed them, Air Vice Marshal Phil Osborn said Friday. The British military released video of two such tanks bursting into flames and smoke.

The United Arab Emirates, meanwhile, announced it will send 12 aircraft in the coming days to help patrol and enforce the United Nations-mandated no-fly zone. And Turkey, once wary of military operations, agreed to the use of an eastern air base in Izmir as a sub-command station.

Other Muslim nations participating in the Libya mission include Qatar, which will begin flying planes this weekend, and Kuwait and Jordan, which have agreed to provide humanitarian or logistical support.

But as the military operation continues, the situation for Libyans caught in battle zones grows more dire by the day, humanitarian agencies reported. The United Nations refugee agency said Friday that increasing numbers of Libyans are displaced from their homes due to fighting.

Refugees streaming out of Ajdabiya described chilling scenes.

"I couldn't even begin to describe to you the horror that I have seen," one man told CNN. "Leaving Ajdabiya we saw dead bodies in the street. No one would ever dare go to recover them."

CNN is not identifying Libyans it has interviewed for their own safety.

Another man said Gadhafi's troops were going house to house in Ajdabiya, hunting for opposition members. He said the troops took away five men from his neighbor's house. He didn't know what happened to them.

Early Friday, coalition warplanes roared again through Libyan skies, bombing the periphery of the capital where military bases are located. Anti-aircraft fire burst out but then fell silent.

International reporters in Tripoli were escorted to farmlands east of Tripoli in Tajura, where Gadhafi's government claims airstrikes killed civilians.

Reporters found no evidence of civilian deaths.

Two military bases along the way had been bombed and were still smoking Friday.

In Tajura, missile fragments lay scattered about a palm orchard and shrapnel had peppered walls of still-standing farm buildings.

One farmer told reporters that a missile landed about 8 p.m. Thursday, but there were no military installations nearby. The missile gouged a small hole in a palm tree and sprayed debris that damaged windows and doors of the farm buildings.

Gadhafi has been keen to put out the word on collateral damage from the coalition's airstrikes. International reporters were taken this week to a seaside cemetery in Tripoli where the funerals of 33 people allegedly killed in airstrikes were taking place.

State television said the dead were victims of the "crusader colonial aggression."

CNN could not independently verify the circumstances of the deaths or who the victims were. In Tripoli, CNN reporters go on government-organized tours in an effort to do their own reporting; Libyan authorities forbid independent movement by international journalists in Tripoli.

The reports of civilian deaths have been given little credence by coalition forces.

"The only civilian casualties we know of for certain are the ones that the Libyan government itself has caused," Gortney has said.

Instead, it is Gadhafi who is almost sure to face serious charges for his brutal crackdown on protesters, said a spokeswoman for the International Criminal Court. The prosecutor of the court is "100 percent" certain Gadhafi will face charges of crimes against humanity once an investigation has been completed, the spokeswoman said.

Meanwhile, the Libyan delegation attending an African Union meeting in Ethiopia said the country is committed to a cease-fire and is ready to let the African Union monitor one.

"We demand the cessation of the air bombardment and the naval blockade carried out by Western forces and the United States for the invalidity of its argument to protect civilians since it is killing them by the hundreds and is attacking and destroying our armed forces and paving the way for the other side to attack," said Mohammed al-Zwai, speaker of the Libyan People's Assembly.

Under an agreement reached Thursday, NATO forces will be able to close Libyan air space to all flights except humanitarian ones and will be able to use force in self-defense.

Michael Burns, a former U.S. ambassador to NATO, said he expects the defense alliance to take over command of the entire operation in a few days to keep up pressure on Gadhafi. The alliance said Friday that Canada's Lt. Gen. Charlie Bouchard, stationed in Naples, Italy, will take the lead for the Libya mission.

"The no-flight zone alone cannot protect the civilians of Libya," Burns told CNN. "Gadhafi is still attacking. ... He is still on the move in some places."

U.N. Secretary-General Ban Ki-moon said he has seen no signs of the cease-fire called for under U.N. Resolution 1973, which was hurriedly passed March 17, as Libyan forces were closing in on the rebel stronghold of Benghazi.

"To the contrary, fierce battles continue in and around the cities of Ajdabiya, Misrata and Zinan," Ban said Thursday, adding his envoy told Libyan authorities that if the government did not comply with the cease-fire resolution, "the Security Council was prepared to take additional measures."

The Libyan conflict was sparked in February by protests against Gadhafi's nearly 42-year rule. The strongman responded with force against civilians, prompting the international community to take action beginning last weekend.